Endel Tulving (1927-2023) transformed the study of memory through his theoretical distinction between episodic and semantic memory and his pioneering research on encoding and retrieval processes. His 1972 distinction between episodic memory (memory for personally experienced events, bound to a specific time and place) and semantic memory (general world knowledge, facts, and concepts, independent of personal experience) was initially controversial but became one of the most fundamental organizing principles in memory research.
Episodic Memory
Tulving characterized episodic memory as involving "mental time travel" — the ability to consciously re-experience past events, including their spatiotemporal context and the subjective feelings associated with them. He distinguished this "autonoetic" (self-knowing) consciousness from the "noetic" (knowing) consciousness associated with semantic memory retrieval. Neuropsychological evidence strongly supports the distinction: patients with hippocampal damage can have severely impaired episodic memory while retaining semantic knowledge, and brain imaging reveals distinct neural signatures for episodic and semantic retrieval.
Tulving's encoding specificity principle states that a retrieval cue is effective to the extent that information about it was encoded at the time of learning. This principle explains why context-dependent memory occurs (better recall in the same environment as learning), why recognition can sometimes fail while cued recall succeeds (when the cue reinstates encoding context more effectively than the recognition test), and why study strategies that create strong cue-target associations produce the best retention. The principle unified diverse memory phenomena under a single theoretical framework.